Autonomous take-off and landing of a tethered aircraft: a simulation study

TL;DR

This paper presents a simulation study of an autonomous tethered aircraft system for airborne wind energy, focusing on launch, flight, and landing using a model-based control approach tested under various wind conditions.

Contribution

It introduces a decentralized control method for autonomous launch and landing of a tethered aircraft, validated through realistic numerical simulations.

Findings

Successful simulation of full launch, flight, and landing cycle

Robust performance under different wind speeds and turbulence

High landing accuracy demonstrated in simulations

Abstract

The problem of autonomous launch and landing of a tethered rigid aircraft for airborne wind energy generation is addressed. The system operates with ground-based power conversion and pumping cycles, where the tether is repeatedly reeled in and out of a winch installed on the ground and linked to an electric motor/generator. In order to accelerate the aircraft to take-off speed, the ground station is augmented with a linear motion system composed by a slide translating on rails and controlled by a second motor. An onboard propeller is used to sustain the forward velocity during the ascend of the aircraft. During landing, a slight tension on the line is kept, while the onboard control surfaces are used to align the aircraft with the rails and to land again on them. A model-based, decentralized control approach is proposed, capable to carry out a full cycle of launch, low-tension flight, and landing again on the rails. The derived controller is tested via numerical simulations with a realistic dynamical model of the system, in presence of different wind speeds and turbulence, and its performance in terms of landing accuracy is assessed. This study is part of a project aimed to experimentally verify the launch and landing approach on a small-scale prototype.